FOSS, Okla. (AP) — Skeletal remains found inside two vehicles that were pulled from an Oklahoma lake may take years to identify, if they are identifiable at all, depending on DNA samples investigators can recover from bones that may have been submerged for decades, authorities said Thursday.

Investigators believe the remains of six people were recovered this week from Foss Lake in western Oklahoma. The bones have been sent to the state medical examiner’s office, which will begin its investigation into whether there was any foul play involved and the cause of death, Custer County Sheriff Bruce Peoples said

The medical examiner will also conduct DNA testing to determine the identities, but Peoples said the success largely hinges on the quality of DNA samples that the remains produce.

The remains were found after a dive team testing sonar equipment discovered two cars in the lake, a 1969 Camaro and an early 1950s Chevrolet. Both vehicles were in only about 12 feet of mucky water about 50 feet from the end of a boat ramp.

Although tests are pending, Peoples said he was confident that the Camaro was carrying three teenagers who disappeared in 1970. Peoples believes the Camaro recovered Tuesday matches closely with the 1969 Camaro owned by Jimmy Williams, who vanished along with classmates Thomas Michael Rios and Leah Johnson while they were driving to a high school football game.

The remains recovered from the other car may be those of two men and a woman who disappeared from the area in 1969.

Amy Elliott, spokeswoman for the medical examiner’s office, said in a statement that an in-house anthropologist would examine the remains. Identification will be attempted through anthropological and possibly forensic pathological methods, she said.

“Depending on the features of these remains and their state of preservation, identification can take anywhere from days to years,” she said in the statement. “In some cases, if the DNA is degraded, positive identification using scientific means may not be possible.”

There is no evidence at this point that there was any criminal activity involved, Peoples said. The sheriff said there was no way to be certain, but that it appears with “high probability” that both cars simply drove down a country road and into the lake.

By Thursday, the scene at Foss Lake had returned to normal and there was little trace of any activity at the ramp. Peoples said the cars were moved to an undisclosed location Wednesday night after investigators finished gathering evidence.

He earlier said he wasn’t surprised the murky waters held a secret.

“This lake isn’t crystal clear. It’s a typical western Oklahoma lake with a lot of silt in it. The visibility is only 6 to 12 inches on a good day,” he said.